A light emitting device includes a P-N junction diode having a characteristic of converting electrical energy into light energy. The light emitting device may be fabricated with the compound of group III-V and group II-VI elements on the Periodic Table. The LED can produce various colors by adjusting the compositional ratio of the compound semiconductors.
For example, a nitride semiconductor represents higher thermal stability and wide bandgap energy so that the nitride semiconductor has been spotlighted in the field of optical devices and high-power electronic devices. For example, blue light emitting devices, green light emitting devices, ultraviolet (UV) light emitting devices, red light emitting devices or the like using nitride semiconductors are commercialized and widely used.
Meanwhile, recently, in a semiconductor industrial field, as the size of various electronic products is reduced, various studies and researches have been carried on to mount more many semiconductor chips on a substrate having a defined size by fabricating a small and high-integrated semiconductor package.
In the field of a light emitting device which is a semiconductor device, a flip-chip mounting technology is applied as a light emitting device mounting technology according to high integration trends.
The flip-chip mounting technology of the light emitting device is a technology of directly mounting a light emitting chip on a package substrate using a solder bump formed of a conductive material.
For example, according to the related art, in a flip-chip mounting structure, solder bumps are formed on a predetermined package substrate, metallic bumps are formed on the light emitting device chip corresponding to the solder bumps, respectively, thereby bonding the solder bumps with the metallic bumps.
However, according to the related art, in the above-described flip-chip mounting structure, peeling may be caused on the interface between an electrode of a light emitting device chip and the metallic bump serving as a connection electrode for a flip-chip, thereby degrading electrical reliability.
In addition, according to the related art, the bonding area between the solder bump of the package substrate and the metallic bump of the light emitting device chip is not insufficiently ensured, so that the electrical characteristic may be degraded.
In addition, according to the related art, an additional contact electrode is formed on the metallic bump of the light emitting device chip through Ni/Au plating. Accordingly, the electrical reliability may be degraded due to the difference in a thermal expansion coefficient between the metallic bump and the contact electrode.
Further, according to the related art, the electrical characteristic of the light emitting device may be degraded due to heat emitted from the light emitting device chip.
In addition, according to the related art, light emitted from the light emitting device chip and reflected upward represents a low reflectance index, so that light extraction efficiency may be lowered.